Phenol content

The composition of coal tar varies with the carbonization method but consists, largely, of mononuclear and polynuclear aromatic compounds and their derivatives. Coke oven tars are relatively low in aliphatic and phenolic content while low-temperature tars have much higher contents of both. 

Wastewater. Phenol is a toxic poUutant to the waterways and has an acute toxicity (- 5 m g/L) to fish. Chlorination of water gives chlorophenols, which impart objectionable odor and taste at 0.01 mg/L. Biochemical degradation is most frequently used to treat wastewater containing phenol. Primary activated sludge, along with secondary biological treatment, reduces phenol content to below 0.1 mg/L (69). 

The reaction may be followed by such tests as melting point, acetone or alcohol solubility, free phenol content or loss in weight on stoving at 135°C. 

Free phenol is a major concern in the manufacture of novolac resins. This is true for several reasons. The strongest drivers are probably EPA classification of phenol as a Hazardous Air Pollutant and worker safety concerns. However, free phenol also has significant technical effects on such parameters as melt flow characteristics. In this role, free phenol may undermine the desired effects of a molecular weight design by increasing flow beyond the desired point. Since free phenol is often variable, the effects on flow may also cause variation in product performance from batch to batch. Fig. 18 shows the effects of free phenol on the flow across a series of molecular weights. Free phenol contents between 1 and 10% are commonly seen. In recent years, much work has been aimed at reducing the free phenol. 

The unknown solution (which should contain between 0.5 and 2.0mg phenol L 1) is treated in the manner described above, and by reference to the calibration curve the absorbance reading will determine the phenol content of the unknown sample. 

Phenol content in various peeling solutions. VXVenner-Kellson... 

ANCos B DE, GONZALES E M and CANO M p (2000) Ellagic acid, vitamin C, and total phenolic contents and radical scavenging capacity affected by freezing and frozen storage in raspberry fruit , J Agric Food Chem, 48 (10) 4565-70. 

Wada, L. and On, B., Antioxidant activity and phenolic content of Oregon caneberries, J. Agric. Food Chem., 50, 3495, 2002. 

The total phenolic content in XRPP was 1.10%. The major components were found to be p-hydroxybenzoic acid (0.44%), vanillin (0.19%), syringic acid (0.13%), and syringaldehyde (0.13%). The contents of p-hydroybenzaldehyde, vanillic acid and ferulic acid were 0.032, 0.015 and 0.020%, respectively. Gallic acid, protocatechuic acid and cinnamic acid were detected in trace amounts. 

Aljadi, A. M. and Kamaruddin, M. Y. (2004). Evaluation of the phenolic contents and antioxidant capacities of two Malaysian floral honeys. Food Chem. 85, 513-518. 

Figure 6. Time course of effects of 10 ug chlorsulfuron per seedling on total phenolic content of sunflower hypocotyls expressed as -coumaric acid equivalents. Reproduced with permission from Ref. 75. Copyright 1983, J. Plant Growth Regul.

Ratios [chloroformate]/[phenol] higher than 1 have been used in order to prepare modified polymers with a degree of substitution lower than 50 (runs 5-7, Table I). Under such conditions it can be noticed that the substitution reactions proceed quantitatively with respect to the initial phenol content. 

Robusta coffee has a somewhat higher phenolic content than Arabica (see Table 7). The feruloylquinic and dicaffeoylquinic acid content in Robusta is higher than in Arabica coffee beans.71 72... 

Ammonia stripping also removes cyanide, phenols, and other VOCs typically found in cokemaking wastewater. Phenols may also be removed by conversion into nonodorous compounds or into crude phenol or sodium phenolate by either biological means (phenol concentration <25 mg/L) or by physical processes.21 However, the Koppers dephenolization process is considered to be quite effective as it lowers the phenol content by 80 to 90% in ammonia still wastes. In this process a stream stripping process followed by mixing in a solution of caustic soda results in renewal of pure phenol with the flue gas.8... 

A possible explanation is that the phenolic content of low rank coal products are too high to allow solubility in even pyridine. This point has yet to be proven, however. 

Based on the tendency for higher levels of phenolics in organically grown plants, these are potentially less susceptible to pests and diseases. Indeed, Schultz and Baldwin (1982) and Rossiter et al., (1986) observed that high phenolic contents reduced the size of female gypsy moth pupae, leading to a decline in reproductive production of female gypsy moths. 

Howard L R, Pandjaitan N, Morelock T, and Gil M L (2002), Antioxidant capacity and phenolic content of spinach as affected by genetics and growing season , JAgric Food Chem, 50, 5891-5896. 

Mpofu A, Sapirstein HD, and Beta T (2006), Genotype and environmental variation in phenolic content, phenolic acid composition, and antioxidant activity of hard spring wheat , J Agric Food Chem, 54, 1265-1270. 

Scalzo J, Politi A, Pellegrini N, Mezzetti B, and Battino M (2005), Plant genotype affects total antioxidant capacity and phenolic contents in fruit , Nutrition, 21, 207-213. 

Feldman, A.W. and Hanks, R.W. (1968). Phenolic content in the roots and leaves of tolerant and susceptible citrus cultivars attacked by Rodopholus similis. 

Yang J, Meyers KJ, van der Heide J and Liu RH. 2004. Varietal differences in phenolic content and antioxidant and antiproliferative activities of onions. J Agric Food Chem 52 6787-6793. 

In order to preserve, as much as possible, the phenolic content in fruit and vegetable samples, the literature proposed the application of cold temperatures, even reaching to freezing, when lyophilization is the objective. These procedures also could inactivate the enzymes. The freeze-drying is largely the main preservation technique used in the studies related to the identification and quantification of the phenolic compounds of fruit... 

Virgin olive oil contains considerable amounts of simple phenols that have a great effect on the stability/sensory and nutritional characteristics of the product. Some of the most representative are hydroxytyrosol (3,4-dihydroxyphenylethanol) and tyrosol (4-hydroxyphenylethanol) however, phenolic compounds are removed when the oil is refined (Tovar and others 2001). The phenolic content of virgin olive oil is influenced by the variety, location, degree of ripeness, and type of oil extraction procedure used, and that is why hydroxytyrosol can be considered as an indicator of maturation for olives (Esti and others 1998). Hydroxytyrosol concentrations are correlated with the stability of the oil, whereas those of tyrosol are not (Visioli and Galli 1998). 

Pastrana-Bonilla E, Akoh CC, Sellappan S and Krewer G. 2003. Phenolic content and antioxidant capacity of muscadine grapes. J Agric Food Chem 51(18) 5497—5503. 

Parr AJ and Bolwell GP. 2000. Phenols in the plant and in man. The potential for possible nutritional enhancement of the diet by modifying the phenols content or profile. J Sci Food Agric 80 985-1012. 

Hukkanen AT, Polonen SS, Karenlampi SO and Kokko HI. 2006. Antioxidant capacity and phenolic content of sweet rowanberries. J Agric Food Chem 54(1) 112—119. 

Ismail A, Marjan ZM and Foong CW. 2004. Total antioxidant activity and phenolic content in selected vegetables. Food Chem 87(4) 581-586. 

Kaur C and Kapoor HC. 2002. Anti-oxidant activity and total phenolic content of some Asian vegetables. Int J Food Sci Technol 37(2) 153-161. 

---